package hotel.meituan.oversea.api.config;

import com.netflix.hystrix.HystrixThreadPoolKey;
import com.netflix.hystrix.HystrixThreadPoolProperties;
import com.netflix.hystrix.strategy.HystrixPlugins;
import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategy;
import com.netflix.hystrix.strategy.concurrency.HystrixRequestVariable;
import com.netflix.hystrix.strategy.concurrency.HystrixRequestVariableLifecycle;
import com.netflix.hystrix.strategy.eventnotifier.HystrixEventNotifier;
import com.netflix.hystrix.strategy.executionhook.HystrixCommandExecutionHook;
import com.netflix.hystrix.strategy.metrics.HystrixMetricsPublisher;
import com.netflix.hystrix.strategy.properties.HystrixPropertiesStrategy;
import com.netflix.hystrix.strategy.properties.HystrixProperty;
import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Callable;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
*@Description: feign 自定义策略
*@Param:
*@return:
*@Author: Zhang·jz
*@date: 2020/9/3
*/
@Slf4j
@Configuration
public class FeignHystrixConcurrencyStrategy extends HystrixConcurrencyStrategy {
   private HystrixConcurrencyStrategy delegate;

   public FeignHystrixConcurrencyStrategy() {
       try {
           this.delegate = HystrixPlugins.getInstance().getConcurrencyStrategy();
           if (this.delegate instanceof FeignHystrixConcurrencyStrategy) {
               // Welcome to singleton hell...
               return;
           }
           HystrixCommandExecutionHook commandExecutionHook =
                   HystrixPlugins.getInstance().getCommandExecutionHook();
           HystrixEventNotifier eventNotifier = HystrixPlugins.getInstance().getEventNotifier();
           HystrixMetricsPublisher metricsPublisher = HystrixPlugins.getInstance().getMetricsPublisher();
           HystrixPropertiesStrategy propertiesStrategy =
                   HystrixPlugins.getInstance().getPropertiesStrategy();
           this.logCurrentStateOfHystrixPlugins(eventNotifier, metricsPublisher, propertiesStrategy);
           HystrixPlugins.reset();
           HystrixPlugins.getInstance().registerConcurrencyStrategy(this);
           HystrixPlugins.getInstance().registerCommandExecutionHook(commandExecutionHook);
           HystrixPlugins.getInstance().registerEventNotifier(eventNotifier);
           HystrixPlugins.getInstance().registerMetricsPublisher(metricsPublisher);
           HystrixPlugins.getInstance().registerPropertiesStrategy(propertiesStrategy);
       } catch (Exception e) {
           log.error("Failed to register Sleuth Hystrix Concurrency Strategy", e);
       }
   }

   private void logCurrentStateOfHystrixPlugins(HystrixEventNotifier eventNotifier,
                                                HystrixMetricsPublisher metricsPublisher, HystrixPropertiesStrategy propertiesStrategy) {
       if (log.isDebugEnabled()) {
           log.debug("Current Hystrix plugins configuration is [" + "concurrencyStrategy ["
                   + this.delegate + "]," + "eventNotifier [" + eventNotifier + "]," + "metricPublisher ["
                   + metricsPublisher + "]," + "propertiesStrategy [" + propertiesStrategy + "]," + "]");
           log.debug("Registering Sleuth Hystrix Concurrency Strategy.");
       }
   }

   @Override
   public <T> Callable<T> wrapCallable(Callable<T> callable) {
       RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
       return new WrappedCallable<>(callable, requestAttributes);
   }

   @Override
   public ThreadPoolExecutor getThreadPool(HystrixThreadPoolKey threadPoolKey,
                                           HystrixProperty<Integer> corePoolSize, HystrixProperty<Integer> maximumPoolSize,
                                           HystrixProperty<Integer> keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue) {
       return this.delegate.getThreadPool(threadPoolKey, corePoolSize, maximumPoolSize, keepAliveTime,
               unit, workQueue);
   }

   @Override
   public ThreadPoolExecutor getThreadPool(HystrixThreadPoolKey threadPoolKey,
                                           HystrixThreadPoolProperties threadPoolProperties) {
       return this.delegate.getThreadPool(threadPoolKey, threadPoolProperties);
   }

   @Override
   public BlockingQueue<Runnable> getBlockingQueue(int maxQueueSize) {
       return this.delegate.getBlockingQueue(maxQueueSize);
   }

   @Override
   public <T> HystrixRequestVariable<T> getRequestVariable(HystrixRequestVariableLifecycle<T> rv) {
       return this.delegate.getRequestVariable(rv);
   }

   static class WrappedCallable<T> implements Callable<T> {
       private final Callable<T> target;
       private final RequestAttributes requestAttributes;

       public WrappedCallable(Callable<T> target, RequestAttributes requestAttributes) {
           this.target = target;
           this.requestAttributes = requestAttributes;
       }

       @Override
       public T call() throws Exception {
           try {
               RequestContextHolder.setRequestAttributes(requestAttributes);
               return target.call();
           } finally {
               RequestContextHolder.resetRequestAttributes();
           }
       }
   }


}
